click below
click below
Normal Size Small Size show me how
BIOL 114
Ch 2: Essential Chemistry
Term | Definition |
---|---|
Acid | A substance that increases the hydrogen ion (H1) concentration in a solution. |
Aqueous solution | A solution in which water is the solvent. |
Atom | The smallest unit of matter that retains the properties of an element. |
Atomic number | The number of protons in each atom of a particular element. |
Base | A substance that decreases the hydrogen ion (H1) concentration in a solution. |
Buffer | A chemical substance that resists changes in pH by accepting hydrogen ions from or donating hydrogen ions to solutions. |
Chemical Bond | An attraction between two atoms resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells. |
Chemical reaction | A process leading to chemical changes in matter, involving the making and/or breaking of chemical bonds. |
Cohesion | The attraction between molecules of the same kind. |
Compound | A substance containing two or more elements in a fixed ratio; for example, table salt (NaCl) consists of one atom of the element sodium (Na) for every atom of chlorine (Cl). |
Covalent bond | An attraction between atoms that share one or more pairs of outer-shell electrons. |
Electron | A subatomic particle with a single unit of negative electrical charge. One or more electrons move around the nucleus of an atom. |
Element | A substance that cannot be broken down into other substances by chemical means. Scientists recognize 92 chemical elements occurring in nature. |
Evaporative cooling | A property of water whereby a body becomes cooler as water evaporates from it. |
Heat | The amount of kinetic energy contained in the movement of the atoms and molecules in a body of matter. Heat is energy in its most random form. |
Hydrogen bond | A type of weak chemical bond formed when a partially positive hydrogen atom from one polar molecule is attracted to the partially negative atom in another molecule (or in another part of the same molecule). |
Ion | An atom or molecule that has gained or lost one or more electrons, thus acquiring an electrical charge. |
Ionic bond | An attraction between two ions with opposite electrical charges. The electrical attraction of the opposite charges holds the ions together. |
Isotope | A variant form of an atom. Isotopes of an element have the same number of protons and electrons but different numbers of neutrons. |
Mass | A measure of the amount of material in an object. |
Mass number | The sum of the number of protons and neutrons in an atom's nucleus. |
Matter | Anything that occupies space and has mass. |
Molecule | A group of two or more atoms held together by covalent bonds. |
Neutron | An electrically neutral particle (a particle having no electrical charge), found in the nucleus of an atom. |
Nucleus | (plural, nuclei) (1) An atom's central core, containing protons and neutrons. (2) The genetic control center of a eukaryotic cell. |
PH scale | A measure of the relative acidity of a solution, ranging in value from 0 (most acidic) to 14 (most basic). pH stands for potential hydrogen and refers to the concentration of hydrogen ions (H1). |
Polar molecule | A molecule containing polar covalent bonds (having opposite charges on opposite ends). |
Products | An ending material in a chemical reaction. |
Proton | A subatomic particle with a single unit of positive electrical charge, found in the nucleus of an atom. |
Radioactive isotope | An isotope whose nucleus decays spontaneously, giving off particles and energy. |
Reactant | A starting material in a chemical reaction. |
Solute | A substance that is dissolved in a solution. |
Solution | A liquid consisting of a homogeneous mixture of two or more substances: a dissolving agent, the solvent, and a substance that is dissolved, the solute. |
Solvent | The dissolving agent in a solution. Water is the most versatile known solvent. |
Temperature | A measure of the intensity of heat, reflecting the average kinetic energy or speed of molecules. |
Trace element | An element that is essential for the survival of an organism but is needed in only minute quantities. |